Preheat oven to 400ºF.  In large bowl, combine flour, sugar, baking powder, cinnamon, and salt; make well in center. In a small bowl combine milk, pumpkin, butter and egg; add to well in flour mixture. Add chocolate chips; stir until dry ingredients are just moistened. Spoon mixture into greased muffin cups, filling each 3/4 full. Sprinkle nuts over each muffin. Bake 18 to 20 minutes. Cool 5 minutes. Remove from pans. Cool completely. Makes 12 regular or 36 tiny muffins.